purpose: to compare central corneal thickness (cct) measured by galilei and orbscan ii with that by ultrasonic (u/s) pachymetry in unoperated eyes. methods: cct was measured in 184 unoperated eyes of 92 healthy retractive surgery candidates using galilei, orbscan ii, and u/s pachymetry. considered as a benchmark, measurements by u/s pachymetry were compared to those obtained by the other two de...

The acoustic effect signif icantly increases the timing jitter of solitons in communication lines. We calculate the correlation in near-neighbor soliton time shifts that result from the acoustic interaction and show that the acoustic effect can cause correlated errors that cannot be corrected with standard, simple error-correction codes such as the Hamming code.

This paper is concerned on the new type of the sensing elements for a particle volume of flow rate measurements based on cross correlation flowmeters. The new type of sensing elements exploit the fact that the solid particles being carried by a flowing air and impacting a properly formed obstacle generate an acoustic surface wave (acoustic emission AE). The acoustic signal is indicated by the a...

We compare two approaches for deriving the fact that the Green’s function in an arbitrary inhomogeneous open system can be obtained by cross correlating recordings of the wave field at two positions. One approach is based on physical arguments, exploiting the principle of time-reversal invariance of the acoustic wave equation. The other approach is based on Rayleigh’s reciprocity theorem. Using...

Several studies have been conducted in recent years that show correlation between high frequency acoustic fluctuations and environmental parameters. For example, effects of tidally driven temperature fluctuations on underwater coherent acoustic communications were studied for a carrier frequency of 18 kHz [1]. However, the relationship between environmental fluctuations and the performance of c...

A series of tests have been conducted to investigate fatigue damage characterization in corroded welded steel plates using structural health monitoring (SHM) techniques. Acoustic Emission (AE) is a non-destructive testing (NDT) technique with potential applications for locating and monitoring fatigue cracks in service. In the present work, AE is implemented to characterize damage during crack e...